Papers by Author: Tie Fan Li

Abstract: Alkali treatment induced to form bonelike apatite layer on the surface of the anodic oxidized Ti6Al4V in 1.5 SBF. It was observed that some spherical apatite crystals were deposited on the surface of the sample for only 1 d. They gradually grew to cover the whole surface of the sample with further increasing soaking time. After 7 days of soaking in 1.5 SBF, apatite covered all the surfaces of the titanium alloys, and they packed very densely and uniformly. At the same time, large amount of new-formed apatite nuclei occurred on the first layer of apatite. The EDS and XRD results proved that all the new-formed phases were composed of apatite. Mechanism of the bioactivity of the anodic oxidized titanium alloys was related to the Ti-OH group formation, and the Ti-OH group would induce apatite formation in SBF.

Abstract: The bioactivity of Ti6Al4V induced by SSPB (supersonic particles bombarding) and alkali treatment was investigated in this work. More coarse surfaces were formed by SSPB and alkali treatment, which led to better bioactivity than that by only alkali treatment. Apatite began to appear on the surface of specimen only after 1 day of immersion in 1.5 SBF. As time passed, they gradually covered the whole surfaces. After 7 days of soaking in vitro, apatite formed and covered all the surfaces of the titanium alloys, and they packed very densely and uniformly. EDS and XRD results proved all the new-formed phases were composed of a carbonate containing hydroxyapatite with small crystallites and defective structure. As a result, SSPB treatment might be an effective way to enhance the bioactivity of titanium alloys for implantation.

Abstract: Nitrogen-doped titania nanoparticles were co-prepared by sol-gel and mechanical-alloying method. Raman spectroscopy was used to investigate the microstructure information of the nitrogen-doped titania nanoparticles. Besides, XPS, ESR and UV-vis absorption spectra were also analyzed as supplementary means. At first blue then red shift of 142 cm-1 peak was observed as the annealing temperatures increased. The possible reasons for the shift were discussed.

Abstract: A layer of amorphous thick anodic oxide film was formed on Ti6Al4V substrate after anodization, and its thickness achieved 30-40µm. After immersion in SBF, anodized sample and substrate indicated different corrosion resistance. According to icorr, Rp and Ecorr, the concerned experimental results of potentiodynamic polarization curves, the anodic oxide film provided effective corrosion protection, which could be attributed to its relatively uniform, smooth, compact and intact microstructure. And the results of total immersion test also proved the protective role of the anodic film.